European monitors said the vote was flawed, with widespread cases of ballot box stuffing and multiple voting.

A group of about 300 protesters had left a market on the outskirts of Bishkek and had gone a short distance towards opposition headquarters when they were intercepted by police, the leader of the opposition United People's Movement, Topchebek Turgunaliev, told the BBC.

The main opposition candidate in the election, Almazbek Atambayev - a former prime minister, secured 8 percent of the vote. He declared the poll "illegitimate" and has called for mass protests against the government.

Mr Bakiyev came to power four years ago off the back of a popular uprising which became known as the Tulip Revolution. He had pledged to conduct free and fair elections.

His political opponents claim their supporters were threatened in the run-up to the election.